Bimetallic Pt-Pd/SiO2-Al2O3 catalysts exhibited much higher activities in aromatic hydrogenation of distillates than monometallic Pt/SiO2-Al2O3 and Pd/SiO2-Al2O3 catalysts. The studies of extended X-ray absorption fine structure (EXAFS) indicated that there was an interaction between Pt and Pd in the Pt-Pd/SiO2-Al2O3 catalyst. Furthermore, from the EXAFS, it was assumed that the active metal particle on the Pt-Pd/SiO2-Al2O3 catalysts is composed of the "Pd dispersed on Pt particle" structure. Regarding both the activities of aromatic hydrogenation and the EXAFS results, it was concluded that the Pd species dispersed on Pt particles were responsible for the high activity of the bimetallic Pt-Pd/SiO2-Al2O3 catalysts.